Upregulation Of Manganese Superoxide Dismutase Research Articles

Preconditioning exercise reduces hippocampal neuronal damage via increasing Klotho expression in ischemic rats

Considerable amounts of oxidants are produced in cerebral ischemia, where oxidative stress plays a key role in neuronal damage after ischemia. Klotho, an anti-aging protein, alleviates oxidative stress by activating the transcription of an important antioxidant enzyme, manganese superoxide dismutase (MnSOD), in the nervous system. Thus, increased Klotho expression level could lead to a reduction in neuronal damages after brain ischemia via lowering oxidative stress. It is known that physical activity increases Klotho expressions. In this study, we assessed neuroprotective effects of preconditioning exercise in rats (treadmill running at a speed of 20 m/min,30 min/day, six days/week, for3 weeks) on hippocampal Klotho and MnSOD expression in the brain using an animal model of stroke, middle cerebral artery occlusion (MCAO). Our study revealed a reduction in hippocampal Klotho and MnSOD expression as well as CA1 neuronal activity in MCAO compared to the sham group. Exercise prevented the ischemia-induced decline in Klotho and MnSOD expression levels as well as CA1 neuronal activity in Exercise + MCAO compared to the MCAO group. Also, exercise significantly improved the neurological scores and reduced brain infarction area in Exercise + MCAO in comparison to MCAO group. There was a post-ischemia deficit in the working memory, as measured by spontaneous alternation percentage using Y-maze test, in MCAO compared to the sham group. The latter effect was not observed in the Exercise + MCAO group, which could be related to an increase in the antioxidant capacity as exhibited by Klotho and MnSOD up-regulation. The results were confirmed with a positive correlation between Klotho expression and MnSOD expression which allows proposing Klotho as a potential neuroprotective protein in ischemic stroke with respect to antioxidant defense. In general, the present study suggested that preconditioning exercise induced upregulation of Klotho and MnSOD, as well as attenuated the post-ischemic injuries. The upregulation of Klotho might be an underlying mechanism by which preconditioning exercise plays as a neuroprotective factor against post-ischemic neural injuries in ischemic rats.

Chronic Low-Dose Alcohol Consumption Attenuates Post-Ischemic Inflammation via PPARγ in Mice.

Ischemic stroke is one of the leading causes of death and permanent disability in adults. Recently, we found that light alcohol consumption (LAC) suppresses post-ischemic inflammatory response, which plays an important role in ischemic brain damage. Our goal was to determine the role of peroxisome proliferator-activated receptor-gamma (PPARγ) in the anti-inflammatory effect of LAC against transient focal cerebral ischemia. In in vivo study, male C57BL/6J wild type (WT) and endothelial-specific conditional PPARγ knockout mice were gavage fed with 0.7 g/kg/day ethanol or volume-matched water daily for 8 weeks. From the 7th week, 3 mg/kg/day GW9662 (a selective PPARγ antagonist) was intraperitoneally given for two weeks. Cerebral ischemia/reperfusion (I/R) injury and expression of manganese superoxide dismutase (MnSOD) and adhesion molecules, neutrophil infiltration, and microglial activation in the cerebral cortex before and following a 90 min unilateral middle cerebral artery occlusion (MCAO)/24 h reperfusion were evaluated. In in vitro study, the impact of chronic alcohol exposure on expression of PPARγ and MnSOD in C57BL/6J mouse brain microvascular endothelial cells (MBMVECs) was measured. PPARγ and MnSOD were significantly upregulated in the cerebral cortex of ethanol-fed WT mice and low-concentration ethanol-exposed C57BL/6J MBMVECs. GW9662 significantly inhibited alcohol-induced upregulation of MnSOD. Eight-week ethanol feeding significantly reduced cerebral I/R injury and alleviated the post-ischemic inflammatory response (upregulation of intercellular adhesion molecule-1 (ICAM-1) and E-selectin, microglial activation, and neutrophil infiltration). Treatment with GW9662 and endothelial-specific conditional knockout of PPARγ did not alter cerebral I/R injury and the inflammatory response in the control mice but abolish the neuroprotective effect in ethanol-fed mice. In addition, GW9662 and endothelial-specific conditional knockout of PPARγ diminished the inhibitory effect of LAC on the post-ischemic expression of adhesion molecules and neutrophil infiltration. Our findings suggest that LAC may protect against cerebral I/R injury by suppressing the post-ischemic inflammation via activation of PPARγ.

Heregulin-β1 Activates NF-E2-related Factor 2 and Induces Manganese Superoxide Dismutase Expression in Human Breast Cancer Cells via Protein Kinase B and Extracellular Signal-regulated Protein Kinase Signaling Pathways.

Heregulin-β1, a ligand of ErbB-2 and ErbB-3/4 receptors, has been reported to potentiate oncogenicity and metastatic potential of breast cancer cells. In the present work, treatment of human mammary cancer (MCF-7) cells with heregulin-β1 resulted in enhanced cell migration and expression of manganese superoxide dismutase (MnSOD) and its mRNA transcript. Silencing of MnSOD abrogated clonogenicity and migrative ability of MCF-7 cells. Heregulin-β1 treatment also increased nuclear translocation, antioxidant response element binding and transcriptional activity of NF-E2-related factor 2 (Nrf2). A dominant-negative mutant of Nrf2 abrogated heregulin-β1-induced MnSOD expression. Treatment with heregulin-β1 caused activation of protein kinase B (Akt) and extracellular signal-regulated protein kinase (ERK). The pharmacological inhibitors of phosphatidylinositol 3-kinase and mitogen-activated protein kinase kinase 1/2, which are upstream of Akt and ERK, respectively, attenuated heregulin-β1-induced MnSOD expression and nuclear localization of Nrf2. In conclusion, heregulin-1 induces upregulation of MnSOD and activation of Nrf2 via the Akt and ERK signaling in MCF-7 cells, which may confer metastatic potential and invasiveness of these cells.

Dynamics of expression of antibacterial and antioxidant defence genes in Indian major carp, Labeo rohita in response to Aeromonas hydrophila infection

Cells produce large number of antioxidant molecules to prevent reactive oxygen species-induced self-damage during microbial assault while generating simultaneously number of antimicrobial molecules to target the pathogen. The present study was aimed at looking into molecules involved in antibacterial and self-protection mechanism of a host Labeo rohita when challenged with a pathogenic bacterium Aeromonas hydrophila. Expression profiles of few of the important host antibacterial genes viz., inducible nitric oxide synthase (iNOS), lysozyme G (LysoG), apolipoprotein A-I (ApoA-I) and hepcidin, and self-defence anti-oxidant genes viz., manganese superoxide dismutase (MnSOD), catalase and glutathione peroxidases (GPx3) were examined in skin and muscle tissues of bacteria challenged fish. Transcription levels of iNOS, LysoG, ApoA-I, hepcidin, catalase, GPx3 and MnSOD were significantly upregulated (P < 0.05) in both tissues at different time points post-bacterial challenge. Increased expression of antibacterial genes in the muscle and skin clearly explains strong defensive mechanism activated in fish tissues in terms of both oxygen-dependent (iNOS) and independent (lysozyme) ways of microbe reduction, and bacterial lysis via production of antimicrobial molecules (ApoA-I and hepcidin) in the host. Simultaneous upregulation of MnSOD, GPx3 and catalase genes explains their involvement in patrolling the cells with regulated production of reactive oxygen species and keeping at a safe level to protect the host's own cells from oxidative damage.

Curcumin enhances liver SIRT3 expression in the rat model of cirrhosis.

Objective(s):Bill duct ligation (BDL) is a representative model of biliary cholestasis in animals. Curcumin has a protective effect on the liver; however, its underlying mechanisms are not completely known. This study explored the hepatoprotective activity of curcumin on hepatic damage via measuring the expression of sirtuin3 (SIRT3), AMP-activated protein kinase (AMPK), carnitine palmitoyltransferase 1A (CPT-1A), isocitrate dehydrogenase2 (IDH2) and manganese superoxide dismutase (MnSOD) as well as the level of serum lipid profile in the BDL fibrotic rat model.Materials and Methods:The study consisted of four groups (n=8 for each of Wistar rats): sham group, sham+curcumin (sham+Cur) group (received curcumin 100 mg/kg/day), BDL+Cur group, and BDL group. Transcription levels of SIRT3, AMPK, CPT-1A, IDH2, MnSOD and protein expression level of SIRT3 were measured by real-time PCR and Western blotting, respectively.Results:It was identified that SIRT3, AMPK, CPT-1A, IDH2 and MnSOD expression significantly decreased in BDL rats compared to sham rats; however, in the curcumin treatment of BDL rats, the expression of these factors increased significantly compared to BDL (P<0.05). It was, moreover, observed that treatment of BDL rats with curcumin reduced liver injury as verified by a reduction in the levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL) and increase in high-density lipoprotein (HDL) (P <0.05).Conclusion:Curcumin reduced liver damage and oxidative stress in the liver tissue of BDL rats through up-regulation of SIRT3, AMPK, CPT-1A, IDH2 and MnSOD as well as changing the level of serum lipid profile.

Abstract 1585: Endostatin inhibits androgen-independent prostate cancer growth by suppressing nuclear receptor-mediated oxidative stress

Abstract Androgen-deprivation therapy has been identified to induce oxidative stress in prostate cancer (PCa), leading to re-activation of androgen receptor (AR) signaling in a hormone-refractory manner. Thus, antioxidant therapies have gained attention as adjuvants for castration-resistant PCa (CRPC). Here, we report for the first time that human endostatin (ES) prevents androgen-independent growth phenotype in PCa cells through its molecular targeting of AR and glucocorticoid receptor (GR), and downstream pro-oxidant signaling. This reversal following ES treatment significantly decreased PCa cell proliferation through downregulation of GR, and upregulation of manganese superoxide dismutase and reduced glutathione levels. Proteome and biochemical analyses of ES-treated PCa cells further indicated a significant upregulation of enzymes in major ROS scavenging machinery, including catalase, glutathione synthetase, glutathione reductase, NADPH-cytochrome P450 reductase, biliverdin reductase and thioredoxin reductase, resulting in a concomitant reduction of intracellular ROS. ES further augmented antioxidant system through upregulation of glucose influx, pentose phosphate pathway (PPP) and NAD salvaging pathway. This shift in cancer cell redox homeostasis by ES significantly decreased the effect of protumorigenic oxidative machinery on androgen-independent PCa growth, suggesting that ES can suppress GR-induced CRPC phenotype upon AR antagonism, and dual targeting action of ES on AR and GR can be further translated to PCa therapy. Citation Format: Joo Hyoung Lee, Minsung Kang, Gurudatta Naik, James A. Mobley, Guru Sonpavde, W. Timothy Garvey, Victor M. Darley-Usmar, Selvarangan Ponnazhagan. Endostatin inhibits androgen-independent prostate cancer growth by suppressing nuclear receptor-mediated oxidative stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1585. doi:10.1158/1538-7445.AM2017-1585

Endostatin inhibits androgen-independent prostate cancer growth by suppressing nuclear receptor-mediated oxidative stress.

Androgen-deprivation therapy has been identified to induce oxidative stress in prostate cancer (PCa), leading to reactivation of androgen receptor (AR) signaling in a hormone-refractory manner. Thus, antioxidant therapies have gained attention as adjuvants for castration-resistant PCa. Here, we report for the first time that human endostatin (ES) prevents androgen-independent growth phenotype in PCa cells through its molecular targeting of AR and glucocorticoid receptor (GR) and downstream pro-oxidant signaling. This reversal after ES treatment significantly decreased PCa cell proliferation through down-regulation of GR and up-regulation of manganese superoxide dismutase and reduced glutathione levels. Proteome and biochemical analyses of ES-treated PCa cells further indicated a significant up-regulation of enzymes in the major reactive oxygen species (ROS) scavenging machinery, including catalase, glutathione synthetase, glutathione reductase, NADPH-cytochrome P450 reductase, biliverdin reductase, and thioredoxin reductase, resulting in a concomitant reduction of intracellular ROS. ES further augmented the antioxidant system through up-regulation of glucose influx, the pentose phosphate pathway, and NAD salvaging pathways. This shift in cancer cell redox homeostasis by ES significantly decreased the effect of protumorigenic oxidative machinery on androgen-independent PCa growth, suggesting that ES can suppress GR-induced resistant phenotype upon AR antagonism and that the dual targeting action of ES on AR and GR can be further translated to PCa therapy.-Lee, J. H., Kang, M., Wang, H., Naik, G., Mobley, J. A., Sonpavde, G., Garvey, W. T., Darley-Usmar, V. M., Ponnazhagan, S. Endostatin inhibits androgen-independent prostate cancer growth by suppressing nuclear receptor-mediated oxidative stress.

Estrogen Protects the Female Heart from Ischemia/Reperfusion Injury through Manganese Superoxide Dismutase Phosphorylation by Mitochondrial p38β at Threonine 79 and Serine 106

A collective body of evidence indicates that estrogen protects the heart from myocardial ischemia/reperfusion (I/R) injury, but the underlying mechanism remains incompletely understood. We have previously delineated a novel mechanism of how 17β-estradiol (E2) protects cultured neonatal rat cardiomyocytes from hypoxia/reoxygenation (H/R) by identifying a functionally active mitochondrial pool of p38β and E2-driven upregulation of manganese superoxide dismutase (MnSOD) activity via p38β, leading to the suppression of reactive oxygen species (ROS) and apoptosis. Here we investigate these cytoprotective actions of E2 in vivo. Left coronary artery ligation and reperfusion was used to produce I/R injury in ovariectomized (OVX) female mice and in estrogen receptor (ER) null female mice. E2 treatment in OVX mice reduced the left ventricular infarct size accompanied by increased activity of mitochondrial p38β and MnSOD. I/R-induced infarct size in ERα knockout (ERKO), ERβ knockout (BERKO) and ERα and β double knockout (DERKO) female mice was larger than that in wild type (WT) mice, with little difference among ERKO, BERKO, and DERKO. Loss of both ERα and ERβ led to reduced activity of mitochondrial p38β and MnSOD at baseline and after I/R. The physical interaction between mitochondrial p38β and MnSOD in the heart was detected by co-immunoprecipitation (co-IP). Threonine 79 (T79) and serine 106 (S106) of MnSOD were identified to be phosphorylated by p38β in kinase assays. Overexpression of WT MnSOD in cardiomyocytes reduced ROS generation during H/R, while point mutation of T79 and S106 of MnSOD to alanine abolished its antioxidative function. We conclude that the protective effects of E2 and ER against cardiac I/R injury involve the regulation of MnSOD via posttranslational modification of the dismutase by p38β.

Simvastatin enhances the hippocampal klotho in a rat model of streptozotocin-induced cognitive decline

Brain oxidative status is a crucial factor in the development of sporadic Alzheimer's disease (AD). Klotho, an anti-aging protein, diminishes oxidative stress by the induction of manganese superoxide dismutase (MnSOD). Thus, the substances that increase klotho expression could be considered as a potential treatment for Alzheimer's disease when the oxidative imbalance is present. Statins are suggested to up-regulate klotho expression. We examined the effect of simvastatin (5mg/kg, daily for 3weeks) on hippocampal klotho and MnSOD expression in the cognitive declined animal model induced by intracerebroventricular (ICV)-streptozotocin (STZ) administration. Cognitive assessment was performed by the Morris Water Maze (MWM) test. The results indicated that mean escape latency and distance were prolonged in the ICV-STZ group compared with the control group. The expression of klotho and MnSOD were also down regulated in the hippocampus. Furthermore, improved spatial performance was observed in simvastatin-treated animals. This effect could be related to increase in oxidative stress tolerance as evidenced by klotho and MnSOD up-regulation. Our current study indicates that klotho upregulation may be a neuroprotective mechanism of simvastatin against cognitive decline in AD.

Abstract 216: The effect of UCP2 upregulation on cellular redox status and mitochondrial respiration

Abstract Uncoupling protein 2 (UCP2) is a mitochondrial protein present in the inner mitochondrial membrane. They belong to the family of anion mitochondrial carriers. UCP2 are thought to have natural antioxidant effect by attenuating the generation of superoxides. Since cancer cells exhibit elevated oxidative stress, they can effectively adapt to this situation by upregulating UCP2. As a matter of fact, UCP2 is overexpressed in many forms of cancer including prostate, breast, lung and head &amp; neck. Not surprising, our early studies demonstrate that knockout of UCP2 suppresses skin tumor formation in a multistage skin carcinogenesis model. The purpose of this study was to detect the impact of UCP2's upregulation on mitochondrial redox status and mitochondrial respiration, using the well characterized tumor promotion model, JB6p+ cells. Our results have demonstrated that UCP2 overexpression enhanced protein expression and activity levels of manganese superoxide dismutase (MnSOD), a mitochondrial-resident enzyme that governs the egression of superoxides. To assess the impact of MnSOD upregulation on mitochondrial redox status, levels of superoxides and hydrogen peroxides were detected. Our results indicated that MnSOD upregulation maintained steady flow of hydrogen peroxides originating from mitochondria. We further examined the effect of UCP2 upregulation-induced MnSOD expression on mitochondrial respiration and glycolytic rate. In agreement with our data, cells overexpressing UCP2 had significantly higher oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). In conclusion, our data suggests that UCP2 promotes carcinogenesis via decreasing superoxide generation whereas promoting hydrogen peroxide production via elevating MnSOD. Collectively, our results support the hypothesis that enhanced UCP2 expression sustains metabolic switch in cancer cells. Citation Format: Annapoorna Sreedhar, Yunfeng Zhao. The effect of UCP2 upregulation on cellular redox status and mitochondrial respiration. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 216.

Poly(ADP-ribose) polymerase 1 contributes to oxidative stress through downregulation of sirtuin 3 during cisplatin nephrotoxicity.

Enhanced oxidative stress is a hallmark of cisplatin nephrotoxicity, and inhibition of poly(ADP-ribose) polymerase 1 (PARP1) attenuates oxidative stress during cisplatin nephrotoxicity; however, the precise mechanisms behind its action remain elusive. Here, using an in vitro model of cisplatin-induced injury to human kidney proximal tubular cells, we demonstrated that the protective effect of PARP1 inhibition on oxidative stress is associated with sirtuin 3 (SIRT3) activation. Exposure to 400 µM cisplatin for 8 hours in cells decreased activity and expression of manganese superoxide dismutase (MnSOD), catalase, glutathione peroxidase (GPX), and SIRT3, while it increased their lysine acetylation. However, treatment with 1 µM PJ34 hydrochloride, a potent PARP1 inhibitor, restored activity and/or expression in those antioxidant enzymes, decreased lysine acetylation of those enzymes, and improved SIRT3 expression and activity in the cisplatin-injured cells. Using transfection with SIRT3 double nickase plasmids, SIRT3-deficient cells given cisplatin did not show the ameliorable effect of PARP1 inhibition on lysine acetylation and activity of antioxidant enzymes, including MnSOD, catalase and GPX. Furthermore, SIRT3 deficiency in cisplatin-injured cells prevented PARP1 inhibition-induced increase in forkhead box O3a transcriptional activity, and upregulation of MnSOD and catalase. Finally, loss of SIRT3 in cisplatin-exposed cells removed the protective effect of PARP1 inhibition against oxidative stress, represented by the concentration of lipid hydroperoxide and 8-hydroxy-2'-deoxyguanosine; and necrotic cell death represented by a percentage of propidium iodide–positively stained cells. Taken together, these results indicate that PARP1 inhibition protects kidney proximal tubular cells against oxidative stress through SIRT3 activation during cisplatin nephrotoxicity.

Activation of AMPK/MnSOD signaling mediates anti-apoptotic effect of hepatitis B virus in hepatoma cells.

To investigate the anti-apoptotic capability of the hepatitis B virus (HBV) in the HepG2 hepatoma cell line and the underlying mechanisms. Cell viability and apoptosis were measured by MTT assay and flow cytometry, respectively. Targeted knockdown of manganese superoxide dismutase (MnSOD), AMP-activated protein kinase (AMPK) and hepatitis B virus X protein (HBx) genes as well as AMPK agonist AICAR and antagonist compound C were employed to determine the correlations of expression of these genes. HBV markedly protected the hepatoma cells from growth suppression and cell death in the condition of serum deprivation. A decrease of superoxide anion production accompanied with an increase of MnSOD expression and activity was found in HepG2.215 cells. Moreover, AMPK activation contributed to the up-regulation of MnSOD. HBx protein was identified to induce the expression of AMPK and MnSOD. Our results suggest that HBV suppresses mitochondrial superoxide level and exerts an anti-apoptotic effect by activating AMPK/MnSOD signaling pathway, which may provide a novel pharmacological strategy to prevent HCC.

Evidence for possible role of melatonin in reducing oxidative stress in multiple sclerosis through its effect on SIRT1 and antioxidant enzymes

AimsOxidative stress plays a crucial role in the pathogenesis of multiple sclerosis (MS). Melatonin has a central role in the modulation of oxidative stress pathways. We aimed to investigate the effect of melatonin on mRNA expression and activity of sirtuin1 (SIRT1) and its target genes, manganese superoxide dismutase (MnSOD), and catalase in peripheral blood mononuclear cells (PBMCs) from MS patients and healthy subjects. Key methodsThis study was performed on 12 patients with relapsing–remitting MS (RRMS) and 14 age- and sex-matched healthy subjects. PBMCs were isolated and treated with pharmacological concentration of melatonin (1mM) for 12h. Gene expression was evaluated by real time-PCR. SIRT1 activity in PBMCs was measured using a fluorometric assay. MnSOD and catalase activities in PBMCs were determined by colorimetric assays. Plasma total antioxidant capacity was measured using the ferric reducing ability of plasma assay. Key findingsMelatonin significantly increased activities and mRNA levels of SIRT1 and catalase in both patients and healthy subjects, whereas melatonin treatment caused a pronounced increase in MnSOD mRNA expression and activity only in patients. In MS patients, SIRT1 activity did not correlate with catalase and MnSOD activities before melatonin treatment, while a significant correlation was observed between SIRT1 activity and catalase activity in PBMCs of patients after melatonin treatment. SignificanceIt appears that the antioxidant status is affected in PBMCs from MS patients and melatonin could improve impaired antioxidant defense in MS through upregulation of SIRT1, MnSOD and catalase, which might be important in MS management.

Inhalation of Talc Induces Infiltration of Macrophages and Upregulation of Manganese Superoxide Dismutase in Rats

Talc is a mineral that is widely used in cosmetic products, antiseptics, paints, and rubber manufacturing. Although the toxicological effects of talc have been studied extensively, until now no detailed inhalation study of talc focusing on oxidative stress has been done. This repeated 4 weeks whole-body inhalation toxicity study of talc involved Sprague-Dawley rats. Male and female groups of rats were exposed to inhaled talc at 0, 5, 50, and 100 mg/m(3) for 6 hours daily, 5 days/week for 4 weeks. The objective was to identify the 4-week inhalation toxicity of talc and investigate antioxidant activity after exposure to talc. There were no treatment-related symptoms or mortality in rats treated with talc. Glucose (GLU) was decreased significantly in male rats exposed to 50 and 100 mg/m(3) of talc. Histopathological examination revealed infiltration of macrophages on the alveolar walls and spaces near the terminal and respiratory bronchioles. In male and female rats exposed to 100 mg/m(3) talc, expression of superoxide dismutase 2, a typical biological indicator of oxidative damage, was significantly increased. Thus, inhalation of talc induces macrophage aggregations and oxidative damage in the lung.

Hydrogen peroxide mediates hyperglycemia-induced invasive activity via ERK and p38 MAPK in human pancreatic cancer.

Diabetes mellitus and pancreatic cancer are intimately related, as approximately 85% of pancreatic cancer patients suffer from glucose intolerance or even diabetes. In this study, we evaluate the underlying mechanism by which hyperglycemia modulates the invasive potential of cancer cells and contributes to their enhanced metastatic behavior. Here we show that hyperglycemia increases the hydrogen peroxide (H2O2) concentration through up-regulation of manganese superoxide dismutase (SOD2) expression, which further activates the ERK and p38 MAPK pathways, as well as the transcription factors NF-κB and AP-1, in a time-dependent manner. The invasion of pancreatic cancer cells resulting from the activation of the H2O2/MAPK axis under high glucose conditions is effectively inhibited by PD 98059 (ERK inhibitor), SB 203580 (p38 MAPK inhibitor), polyethylene glycol-conjugated catalase (PEG-CAT), or the siRNA specific to SOD2. In addition, streptozotocin-treated diabetic nude mice exhibit a stronger tumor invasive ability in renal capsule xenografts which could be suppressed by PEG-CAT treatment. Furthermore, the integrated optical density (IOD) of SOD2 and uPA stainings is higher in the tumor tissues of pancreatic cancer patients with diabetes compared with pancreatic cancer patients with euglycemia. Taken together, our results demonstrate that hyperglycemia enhances cell invasive ability through the SOD2/H2O2/MAPK axis in human pancreatic cancer. Thus, SOD2/H2O2/MAPK axis may represent a promising therapeutic target for pancreatic cancer patients combined with diabetes mellitus.

DJ-1 Mediates the Delayed Cardioprotection of Hypoxic Preconditioning Through Activation of Nrf2 and Subsequent Upregulation of Antioxidative Enzymes.

We have recently shown that DJ-1 is implicated in the delayed cardioprotective effect of hypoxic preconditioning (HPC) against hypoxia/reoxygenation (H/R) injury as an endogenous protective protein. This study aims to further investigate the underlying mechanism by which DJ-1 mediates the delayed cardioprotection of HPC against H/R-induced oxidative stress. Using a well-characterized cellular model of HPC from rat heart-derived H9c2 cells, we found that HPC promoted nuclear factor erythroid 2-related factor 2 (Nrf2) and its cytoplasmic inhibitor Kelch-like ECH-associated protein-1 (Keap1) dissociation and resulted in increased nuclear translocation, antioxidant response element-binding, and transcriptional activity of Nrf2 24 hours after HPC, with subsequent upregulation of manganese superoxide dismutase (MnSOD) and heme oxygenase-1 (HO-1), which provided delayed protection against H/R-induced oxidative stress in normal H9c2 cells. However, the aforementioned effects of HPC were abolished in DJ-1-knockdown H9c2 cells, which were restored by restoration of DJ-1 expression. Importantly, we showed that inhibition of the Nrf2 pathway in H9c2 cells mimicked the effects of DJ-1 knockdown and abolished HPC-derived induction of antioxidative enzymes (MnSOD and HO-1) and the delayed cardioprotection. In addition, inhibition of Nrf2 also reversed the effects of restored DJ-1 expression on induction of antioxidative enzymes and delayed cardioprotection by HPC in DJ-1-knockdown H9c2 cells. Taken together, this work revealed that activation of Nrf2 pathway and subsequent upregulation of antioxidative enzymes could be a critical mechanism by which DJ-1 mediates the delayed cardioprotection of HPC against H/R-induced oxidative stress in H9c2 cells.

Mn-SOD Upregulation by Electroacupuncture Attenuates Ischemic Oxidative Damage via CB1R-Mediated STAT3 Phosphorylation.

Electroacupuncture (EA) pretreatment elicits the neuroprotective effect against cerebral ischemic injury through cannabinoid receptor type 1 receptor (CB1R). In current study, we aimed to investigate whether the signal transducer and activator of transcription 3 (STAT3) and manganese superoxide dismutase (Mn-SOD) were involved in the antioxidant effect of EA pretreatment through CB1R. At 2 h after EA pretreatment, focal cerebral ischemic injury was induced by transient middle cerebral artery occlusion for 60 min in C57BL/6 mice. The expression of Mn-SOD in the penumbra was assessed by Western blot and immunoflourescent staining at 2 h after reperfusion. In the presence or absence of Mn-SOD small interfering RNA (siRNA), the neurological deficit score, the infarct volume, the terminal deoxynucleotidyl transferase-mediated dUDP-biotin nick end labeling (TUNEL) staining, and oxidative stress were evaluated. Furthermore, the Mn-SOD protein expression and phosphorylation of STAT3 at Y705 were also determined in the presence and absence of CB1R antagonists (AM251, SR141716) and CB1R agonists (arachidonyl-2-chloroethylamide (ACEA), WIN 55,212-2). EA pretreatment upregulated the Mn-SOD protein expression and Mn-SOD-positive neuronal cells at 2 h after reperfusion. EA pretreatment also attenuated oxidative stress, inhibited cellular apoptosis, and induced neuroprotection against ischemic damage, whereas these beneficial effects of EA pretreatment were reversed by knockdown of Mn-SOD. Mn-SOD upregulation and STAT3 phosphorylation by EA pretreatment were abolished by two CB1R antagonists, while pretreatment with two CB1R agonists increased the expression of Mn-SOD and phosphorylation level of STAT3. Mn-SOD upregulation by EA attenuates ischemic oxidative damage through CB1R-mediated STAT3 phosphorylation in stroke mice, which may represent one new mechanism of EA pretreatment-induced neuroprotection against cerebral ischemia.

Free Fatty Acids, Lipopolysaccharide and IL-1α Induce Adipocyte Manganese Superoxide Dismutase Which Is Increased in Visceral Adipose Tissues of Obese Rodents

Excess fat storage in adipocytes is associated with increased generation of reactive oxygen species (ROS) and impaired activity of antioxidant mechanisms. Manganese superoxide dismutase (MnSOD) is a mitochondrial enzyme involved in detoxification of ROS, and objective of the current study is to analyze expression and regulation of MnSOD in obesity. MnSOD is increased in visceral but not subcutaneous fat depots of rodents kept on high fat diets (HFD) and ob/ob mice. MnSOD is elevated in visceral adipocytes of fat fed mice and exposure of differentiating 3T3-L1 cells to lipopolysaccharide, IL-1α, saturated, monounsaturated and polyunsaturated free fatty acids (FFA) upregulates its level. FFA do not alter cytochrome oxidase 4 arguing against overall induction of mitochondrial enzymes. Upregulation of MnSOD in fat loaded cells is not mediated by IL-6, TNF or sterol regulatory element binding protein 2 which are induced in these cells. MnSOD is similarly abundant in perirenal fat of Zucker diabetic rats and non-diabetic animals with similar body weight and glucose has no effect on MnSOD in 3T3-L1 cells. To evaluate whether MnSOD affects adipocyte fat storage, MnSOD was knocked-down in adipocytes for the last three days of differentiation and in mature adipocytes. Knock-down of MnSOD does neither alter lipid storage nor viability of these cells. Heme oxygenase-1 which is induced upon oxidative stress is not altered while antioxidative capacity of the cells is modestly reduced. Current data show that inflammation and excess triglyceride storage raise adipocyte MnSOD which is induced in epididymal adipocytes in obesity.

Abstract 76: Toll-Like Receptor 4 Deficiency Protects C3H/HeJ Mice from Angiotensin-II Induced Renovascular Fibrosis

Toll-like receptor 4 (TLR4) is a molecule involved in innate immune response. Current evidence suggests that activation of TLR4 is associated with vascular and cardiac remodeling by a process which involves production of reactive oxygen species and inflammatory cytokines. Oxidative stress is well established in the development of renal fibrosis in chronic hypertension. In this study, we hypothesized that TLR4 deficiency in C3H/HeJ (C3H) mice protects the kidney from angiotensin induced renal remodeling by reducing mitochondrial oxidative stress. Wildtype (WT) and C3H mice were implanted with osmotic pumps loaded without or with Angiotensin-II (Ang-II) for delivery at 250 ng/kg/min for 4 weeks. Animal groups were 1) WT + Saline, 2) WT + Ang-II, 3) C3H + Saline, 4) C3H + Ang-II. Blood pressure was measured weekly and end-point laser Doppler flowmetry was done to assess renal cortical blood flow. Superoxide content was measured by dihydroethidium staining. Mitochondrial oxidative stress was measured by H 2 O 2 production, manganese superoxide dismutase (MnSOD) and catalase was measured by gel and assay method respectively. Ang-II administration induced higher blood pressure in WT mice than in C3H mice (135.8 ± 5.1 vs. 109.4 ± 5.6 mm of Hg). Ang-II decreased renal cortical flux to a greater degree in WT mice compared to C3H mice [1052.8 ± 67.8 vs. 1182.9 ± 24.7 perfusion units (PU)]. Superoxide content was increased in WT + Ang-II mice compared to C3H + Ang-II. The expression and activity of mitochondrial MnSOD was increased in C3H mice compared to WT mice receiving Ang-II. H 2 O 2 production was increased in C3H + Ang-II compared to WT mice receiving similar treatment. Collagen accumulation and wall-to-lumen ratio was increased in the cortical vessels of WT mice compared to C3H mice receiving Ang-II indicating fibrosis. C3H mice also exhibited lower levels of inflammatory cytokines TGF-β, TNF-α and IL-6 than WT mice receiving Ang-II. Our data suggests that in TLR4 deficiency (C3H mice), upregulation of mitochondrial MnSOD reduces reactive oxygen species production and inflammation and thus renovascular remodeling in Ang-II induced hypertension.

The NF-κB Inhibitory Proteins IκBα and IκBβ Mediate Disparate Responses to Inflammation in Fetal Pulmonary Endothelial Cells

Exposure to intrauterine inflammation impairs lung growth but paradoxically protects the neonatal pulmonary vasculature from hyperoxic injury. The mechanisms mediating these contradictory effects are unknown. The objective is to identify the role of NF-κB in mediating cytoprotective and proinflammatory responses to inflammation in the fetal pulmonary endothelium. In newborn rats exposed to intra-amniotic LPS, we found increased expression of the NF-κB target gene manganese superoxide dismutase (MnSOD) in the pulmonary endothelium. Supporting these in vivo findings, LPS induced NF-κB activation and MnSOD expression in isolated fetal pulmonary arterial endothelial cells. In addition, LPS exposure caused apoptosis and suppressed cellular growth and induced P-selectin expression. LPS-induced NF-κB activation that proceeded through specific isoforms of the inhibitory protein IκB mediated these diverse responses; NF-κB signaling through IκBα degradation resulted in MnSOD upregulation and preserved cell growth, whereas NF-κB signaling through IκBβ degradation mediated apoptosis and P-selectin expression. These findings suggest that selective inhibition of NF-κB activation that results from IκBβ degradation preserves the enhanced antioxidant defense and protects the developing pulmonary vascular endothelium from ongoing inflammatory injury.